Characteristics and Outcomes of Adults With Congenital Heart Disease in the Cardiac Intensive Care Unit

Background Little is known regarding the characteristics, treatment patterns, and outcomes in patients with adult congenital heart disease (ACHD) admitted to cardiac intensive care units (CICUs). Objectives The authors sought to better define the contemporary epidemiology, treatment patterns, and outcomes of ACHD admissions in the CICU. Methods The Critical Care Cardiology Trials Network is a multicenter network of CICUs in North America. Participating centers contributed prospective data from consecutive admissions during 2-month annual snapshots from 2017 to 2022. We analyzed characteristics and outcomes of admissions with ACHD compared with those without ACHD. Multivariable logistic regression was used to assess mortality in ACHD vs non-ACHD admissions. Results Of 23,299 CICU admissions across 42 sites, there were 441 (1.9%) ACHD admissions. Shunt lesions were most common (46.1%), followed by right-sided lesions (29.5%) and complex lesions (28.7%). ACHD admissions were younger (median age 46 vs 67 years) than non-ACHD admissions. ACHD admissions were more commonly for heart failure (21.3% vs 15.7%, P < 0.001), general medical problems (15.6% vs 6.0%, P < 0.001), and atrial arrhythmias (8.6% vs 4.9%, P < 0.001). ACHD admissions had a higher median presenting Sequential Organ Failure Assessment score (5.0 vs 3.0, P < 0.001). Total hospital stay was longer for ACHD admissions (8.2 vs 5.9 days, P < 0.01), though in-hospital mortality was not different (12.7% vs 13.6%; age- and sex-adjusted OR: 1.19 [95% CI: 0.89-1.59], P = 0.239). Conclusions This study illustrates the unique aspects of the ACHD CICU admission. Further investigation into the best approach to manage specific ACHD-related CICU admissions, such as cardiogenic shock and acute respiratory failure, is warranted.

T he population of patients with adult congenital heart disease (ACHD) is growing rapidly. 1,24][5] Compared to the general population, patients with ACHD have an increased likelihood of requiring admission to an intensive care unit (ICU) and have a higher mortality for many common noncardiovascular conditions requiring hospitalization. 6HD patients are highly diverse with unique anatomy, hemodynamics, and extracardiac physiology that requires special consideration, particularly in the setting of critical illness. 7,8Where available, ACHD patients hospitalized with critical illness are typically admitted to a specialized cardiac intensive care unit (CICU).There is a paucity of data describing the epidemiology, patient characteristics, and resource utilization in critically ill patients with ACHD.
We used a large prospective North American reg- previously. 9Scientific oversight of CCCTN is conducted by its academic executive and steering com- The CCCTN registry protocol and waiver of informed   P < 0.0001) (Figure 3).CICU mortality (   Heart failure was the leading cause of ACHD admission to the CICU in our study, accounting for over 20% of all ACHD admissions.Heart failure was also the greatest contributor to deaths among ACHD admissions, accounting for 30% of deaths.This finding is consistent with previous studies in which ACHD patients admitted for heart failure had prolonged lengths of stay and higher in-hospital and 1-year mortalities compared to ACHD patients without heart failure. 16,17Heart failure is a heterogenous condition in ACHD and is often difficult to accurately capture solely with a left ventricular ejection fraction-focused classification, particularly in patients with Fontan or single ventricle physiology, systemic right ventricles, or severe pulmonary hypertension and right ventricular failure.This aspect can make it challenging to identify and treat such patients, particularly in centers without sufficient experience in advanced therapeutic options for ACHD.However, the rapid identification and escalation of treatment to advanced therapies for ACHD may be instrumental to prevent morbidity and mortality in this patient population.Despite the high proportion of admissions for heart failure in the ACHD group and higher utilization of vasopressors among ACHD admissions, admissions for cardiogenic  shock were similar between both ACHD and non-ACHD admissions.This contrast may be in part due to an under recognition of low output states in the ACHD population given their complex physiology and prevalent cyanosis.Previous studies have found ACHD patients less frequently receive both temporary and durable MCS, likely due to more complex anatomy and more comorbid conditions. 18,19In our registry, MCS utilization was w10% for both ACHD and non-ACHD admissions, which may represent a paradigm shift toward wider use of temporary MCS in the ACHD population, although our overall sample was small and the specialized centers in our study may be more willing to adapt new technologies to this complex patient cohort. CRITICAL CARE FOR PATIENTS WITH ACHD.Previous studies have highlighted increased ICU admissions and overall health care spending in the ACHD population relative to the general population. 5,6Our study found that ACHD admissions to CICUs specifically had higher utilization of certain ICU resources, namely noninvasive positive pressure ventilation, high flow nasal cannula, and invasive hemodynamics (pulmonary artery catheters and arterial lines).The emphasis on noninvasive oxygen support may be in part due to the chronic hypoxemia observed in many patients with ACHD, particularly with shunt or single ventricle physiology.The high prevalence of restrictive lung disease in Fontan and Tetralogy of Fallot patients may also contribute to the greater oxygen therapy utilization. 20Our study also found that admissions with ACHD more often underwent invasive hemodynamic monitoring with arterial lines and pulmonary artery catheters, despite similar incidences of cardiogenic shock.This is likely in part explained by the higher use of vasopressors in the ACHD admissions group and the need for invasive hemodynamics.Additionally, the presence of baseline cyanosis and organ dysfunction in patients with ACHD, particularly in Fontan patients, makes it much more challenging on physical examination and laboratory testing to accurately quantify how critically ill a patient is and may prompt a lower threshold for invasive hemodynamics.
CICU OUTCOMES FOR PATIENTS WITH ACHD.ACHD admissions had longer CICU and total hospital lengths of stay; however, mortality and CICU readmission rates were similar between both groups despite the substantially younger age of admissions with ACHD.
With adjustment for age and sex, the odds of death remained similar for admissions with and without ACHD.Interestingly, after adjusting additionally for the greater severity of the presenting illness (using the SOFA score) among admissions with ACHD, CICU mortality was numerically lower in the ACHD group.
There is likely heterogeneity within the ACHD patient population; a patient with Fontan circulation presenting in cardiogenic shock and Fontan heart failure is likely to carry a worse prognosis than a patient with an atrial septal defect presenting in atrial arrhythmia.
Nevertheless, regardless of survival status, CICU presentation with more severe organ dysfunction is an important characteristic of the epidemiology of ACHD patients in the CICU.Future exploration to determine contributing causes could be important from a health care utilization and cost-effectiveness perspective.Also important to note is that even though mortality is similar between ACHD and non-ACHD admissions, the younger age of the ACHD population at the time of death represents a substantial burden of disease for this population.Even in those with ACHD who survive, it is likely that the  significant comorbidity burden in this population carries a disproportionately heavy toll in younger patients who are navigating the challenges of starting families and growing careers.
As the burden of congenital heart disease mortality shifts from the pediatric to adult population, patients with ACHD will continue to have an increased burden of comorbidities, both related to their extracardiac manifestations of disease, as well as more common cardiac conditions such as coronary artery disease, diabetes, and hypertension. 1As this population continues to grow and age, it will be necessary for the contemporary CICU to be prepared to meet the needs of this highly comorbid and unique patient population.TRANSLATIONAL OUTLOOK: Further investigation into the best therapeutic options for patients with ACHD admitted to the CICU is needed to best serve this patient population.
istry of admissions to CICUs to describe the baseline characteristics, treatment patterns, and outcomes in ACHD admissions to the CICU.METHODS CRITICAL CARE CARDIOLOGY TRIALS NETWORK REGISTRY.The Critical Care Cardiology Trials Network Registry (CCCTN) is an investigatorinitiated, collaborative network of American Heart Association level 1 CICUs in the United States and Canada.Details of the inception, conduct, and methods of the CCCTN registry have been reported mittees and is coordinated by the TIMI Study Group, Brigham and Women's Hospital, Boston, Massachusetts.All participating investigators and study coordinators undergo central CCCTN training on data collection and the central coordinating center reviews all cases for consistency.Participating centers contributed at least annual 2-month data "snapshots" of consecutive medical admissions to the CICU from 2017 through 2022.Only the first CICU admission during a hospitalization was collected; readmission to the CICU was recorded, but no further data for the subsequent CICU stay during the same hospitalization was collected.A patient admitted in two separate snapshots (eg, 2017 and 2019) would be recorded twice as these were two separate CICU admissions.A detailed description of the data elements recorded for the CCCTN registry has been reported previously. 10 SOFA score and more frequently utilized advanced respiratory therapies, vasopressors, and invasive hemodynamics.Finally, ACHD admissions had longer lengths of stay in the CICU and in the hospital, but despite their substantially younger age, had similar rates of CICU readmission and in-hospital mortality.These quantitative data fill a gap in the epidemiology of this important growing population.CLINICAL PRESENTATION OF PATIENTS WITH ACHDREQUIRING CRITICAL CARE.ACHD patients are known to have increased rates of atrial arrhythmias, pulmonary hypertension, and liver disease.4,[13][14][15]Our study quantifies extracardiac comorbidities as another key driver of their CICU admission, as "general medical problems" (ie, liver and renal failure, hypoxic respiratory failure, sepsis) were the second most common admission diagnosis for ACHD admissions.Mortality was not uniform across admission diagnoses; while no ACHD admissions primarily for atrial arrhythmia died, admissions for general medical problems contributed nearly 20% of the total deaths among ACHD admissions.These findings emphasize the need for clinical expertise and training in both cardiac and extracardiac complications of ACHD in the CICU setting.

FIGURE 1
FIGURE 1 Primary Admission Diagnosis Stratified by Admissions With and Without Adult Congenital Heart Disease

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A C C : A D V A N C E S , V O L . 3 , N O .8 , 2 0 2 4

FIGURE 2
FIGURE 2 Cardiac Intensive Care Unit Resource Utilization Stratified by Admissions With and Without Adult Congenital Heart Disease

FIGURE 3
FIGURE 3 Cardiac Intensive Care Unit and Hospital Length of Stay Stratified Admissions With and Without Adult Congenital Heart Disease STUDY LIMITATIONS.There are limitations to our current study.The CCCTN registry collects observational data on only medical CICU admissions; thus, it does not evaluate ACHD patients admitted to other ICUs, including pediatric CICUs.As discussed above, our registry only records data for the first CICU admission in a given hospitalization, and thus does not inherently represent a complete analysis of a patient's CICU resource utilization over time.Additionally, only in-hospital outcomes are collected for the CCCTN registry, and data regarding postdischarge outcomes are not collected.Data are collected by chart review by site investigators and are subject to PERSPECTIVES COMPETENCY IN MEDICAL KNOWLEDGE: Patients with ACHD admitted to the CICU require a unique subset of ICU therapies and expertise in both cardiac and noncardiac comorbidities related to their disease.

Table 5
[95% CI: 0.70-1.22],P¼0.573).Moreover, adjusting for age and sex, there remained no significant difference in adjusted CICU or in-hospital mortality (Table5).Accounting for baseline severity of organ dysfunction by adjusting additionally for SOFA score, the odds of death in the CICU was lower for ACHD vs non-ACHD admissions (OR: 0.65 [95% CI: 0.43-0.98],P¼ 0.037), with a concordant trend in hospital mortality (OR: 0.85 [95% CI: 0.61-1.18],P¼ 0.326).ventriclephysiology and/or Fontan circulation.Admissions with ACHD were on average 20 years younger and had a unique profile of admissions diagnoses, namely more liver disease, atrial arrhythmias, and pulmonary hypertension than non-ACHD admissions.Admissions with ACHD also had a higher

TABLE 3
Number of Admissions in Each of the Congenital Heart

TABLE 4
Admissions and Worst Laboratory Values Stratified by Admissions With and Values are median (25th-75th percentile) or n (%). a Worst lab value within 24 h of admission.ACHD ¼ adult congenital heart disease; ALT ¼ alanine transferase; eGFR ¼ estimated glomerular filtration rate; SOFA ¼ Sequential Organ Failure Assessment.

TABLE 5
Cardiac Intensive Care Unit and Hospital Mortality in Patients With and Without Values are n (%) or OR (95% CI).ACHD ¼ adult congenital heart disease; CICU ¼ cardiac intensive care unit; SOFA ¼ sequential organ failure score.

TABLE 6
Mortality Rates Stratified by Primary Admission Diagnosis in Adult Congenital Stout KK, Daniels CJ, Aboulhosn JA, et al. 2018 AHA/ACC guideline for the management of adults with congenital heart disease: executive summary: a report of the American College of cardiology/ American heart Association Task Force on clinical Practice guidelines.J Am Coll Cardiol.2019;73: 1494-1563.12. Vincent JL, Moreno R, Takala J, et al.The SOFA (Sepsis-related organ failure Assessment) score to describe organ dysfunction/failure.On behalf of the working group on sepsis-related problems of the European society of intensive care medicine.Intensive Care Med.1996;22: 707-710.